In one episode of B5, Ivanova makes the comment, “We’re not a deep space franchise.”
Hmmm. . . .
So if they say something about “underwater” on Sea Hunt they were ripped of by Voyage To The Bottom Of The Sea?
I don’t think the similarities mean all that much. However, it is clear that DS9 was created in reaction to B5. Paramount passed on B5 and indicated they weren’t interested in a ST spinoff. However, once WB began production on B5, Paramount suddenly changed their minds and announced they were doing DS9, and the concept was quite similar to B5 (without the story arc idea).
It’s clear that Paramount jumped in because of B5, and may have taken some elements of JMS’s pitch to them. But, really, that’s SOP for TV – something succeeds and you rip off the idea.
They both ripped off “Tom Swift and His Flying Lab”, dang it.
I don’t know if I’d call B5 “successful” in television executive terms. Certainly not on the same level as even the weakest of the Trek franchise. It’s certainly successful in an artistic sense but since when is successful art copied for television.
JMS has definitely taken inspiration for the majority of his story from various classic sources. He doesn’t deny it and it would be pointless to even try. Trek took inspiration likely from the fact that the continuing story arc was becoming more prominant in television at the time. The obvious continuing story are invading evil aliens and conspiracies and they have an easy base for that as a continuing character already.
FWIW, Straczynski himself in the past has been more than willing to say it’s likely a coincidence.